1. Field of the Invention
The invention relates to a radial-flow exhaust turbocharger turbine with a row of individually adjustable guide vanes which can be turned by means of respective adjusting shafts supported in a casing, each adjusting shaft being actuated by means of a pivoting lever.
2. Discussion of Background
Turbines of this kind are sufficiently well known in exhaust turbochargers, for example, adjustment of the guide vanes at the turbine being a possible measure. Examples of this are provided by EP 226 444 B1 or EP 227 475 B1. The adjustable turbine guide vanes are intended to produce a larger gradient for a given throughput. This increases the turbine power, the turbine rotational speed and, finally, the boost pressure. In order to prevent the adjustable vanes from jamming during "hot" operation, they must, generally speaking, be installed with appropriate clearance. Particularly in the closed-down condition, the flow through the gaps at the tip and the root of the vanes can have a very disturbing effect on the main flow in the duct. In the machine according to EP 226 444 B1, this situation is remedied by designing the duct wall of the casing to be axially displaceable next to the turnable blade and pressing it against the adjustable vanes during operation.
In general, as can be seen from EP 226 444 B1 or EP 227 475 B1, the pivoting levers are driven by a common grooved ring. This grooved ring is rotatable and must therefore be bearing-mounted. The drive shafts of the adjustable vanes are furthermore smaller in diameter than the chords of the adjustable vanes. As a result, the pivoting lever must, for example in the event of vane removal, be separated from the adjusted shaft.